The present invention relates to an apparatus and method for recording and reproduction of contents with the use of a removable content storage medium having a high copyright protection function, i.e., high security level.
With recent digital broadcast, in view of copyright protection, contents are provided after being encrypted with the addition of a restricting signal such as “one-time copy only”. Accordingly, with a digital-broadcast-ready recorder, contents are stored in a storage medium such as hard disk drive (HDD) after being uniquely encrypted, thereby preventing leakage of contents due to unauthorized use or human error, for example. For writing of contents recorded on an HDD onto a DVD (Digital Versatile Disc) or a Blu-ray Disc™, for example, the contents recorded on the HDD are to be removed (move function), thereby following the predetermined rule of “one-time copy only”.
The issue here is that the contents cannot be stored on any removable hard disk as having been uniquely encrypted before storage on the hard disk. Even if the contents can be stored on such a removable hard disk, the resulting disk will not work on any other types of apparatuses, and thus users find it inconvenient. In consideration thereof, a removable hard disk “iVDR Secure™” has appeared on the market with the copyright protection function. This “iVDR Secure” is in conformity with SAFIA (Security Architecture For Intelligent Attachment device) being the copyright protection technology, and includes various functions for implementation of the copyright protection function for the contents. The various functions include the function of managing encrypted content data separately from a Usage Pass being key information including a decoding key for the content data, the function of protecting the Usage Pass in storage from any unauthorized access, and the function of transferring the Usage Pass with PKI (Public Key Infrastructure)-based two-way authentication. Moreover, using such copyright protection function for the contents, specifications are defined for music players mainly for music contents and for video players mainly for video contents. With the video players, a logical block of 3072 bytes being the result of video stream division is referred to as Aligned Unit (AU), and content encryption is performed by the unit of this AU. A logical block being a collection of 512 successive Aus is referred to as Allocation Unit (ALU), and this ALU is the minimum unit for content encryption by one Usage Pass. For implementing the content move function, there needs to change the Usage Pass in a minute or less with the SAFIA because the time allowed for content duplication is a minute or shorter. Examples include Patent Document 1 (JP-A-2007-95204), and Non-Patent Document 1 (Recording and Playback Device for iVDR—TV Recording specification (http://www.safia-lb.com/doc/spec/SAFIA_RPD_TV_V120—200802 21.pdf)).
With a recorder using a storage medium being such an SAFIA-conformed “iVDR Secure”, contents stored in the “iVDR Secure” are normally reproduced in the following manner, i.e., mutual authentication is performed between the recorder body and the “iVDR Secure”, a communications path is established for encryption using a Usage-Pass transfer protocol between the recorder body and the “iVDR Secure”, the Usage Pass is read with security, any separately-read encrypted contents are decoded using an encryption key stored in the Usage Pass, and the resulting data is passed to a decoder. With the recorder body and the “iVDR Secure” as such, however, there is a concern that it may take a long time to read the Usage Pass with security because the CPU (Central processing Unit) in use is of a built-in type with the processing capability being not sufficiently high. If this is the case, there is a possibility of causing screen disturbance because reading of the Usage Pass takes too long for normal reproduction. Moreover, when a plurality of vendors provide their own “iVDR Secure”, for example, the time needed to read the Usage Pass with security may possibly vary among the vendors. For implementing special reproduction such as fast forward or fast rewind, there needs to read the Usage Pass and the contents at a speed corresponding to the fast speed. The contents made for digital broadcast are referred to as MPEG2 (Motion Picture Experts Group 2) TS (Transport Stream), and for special reproduction thereof, there are at least needs to display a plurality (n) of frames (I frames) in a minute, and to make a frame selection at predetermined time intervals for display, e.g., if with an X-speed, y frame (s) in x minutes are selected at intervals of y/n so as to display the x-minute-after frame after a minute. Such an operation is required to be executed at the same time as reading of the Usage Pass that is completed in less than a minute. As such, implementing special reproduction will be difficult when reading of the Usage Pass takes a long time.